Grok Pattern for date and time format "03-MAR-21 00:40:21"

[Wilks]

This is likely a simple one but what's the grok pattern for this? I have gone through all the ones I could find but I cant get a match for the format 03-MAR-21 00:40:2

Currently I am using a string but need to change it from a string to a time as its causing reporting issues

grok   {
         match => { "message" => [ "%{GREEDYDATA:timestamp}
          }

date {
        match => [ "timestamp", "dd-MMM-yy HH:mm:ss" ]
        target => "@timestamp"
      }

[Badger]

That appears to match the core TIMESTAMP_ISO8601 pattern, so you could use

grok {  match => { "message" => "%{TIMESTAMP_ISO8601 :timestamp}" }  }

I normally think of ISO8601 dates as having four digit years, but the pattern works with two as well.

[Wilks]

Thanks for the response.
I tried that but I get "_grokparsefailure". If I try "%{TIMESTAMP_ISO8601:timestamp}" on the grok debugger tool it fails as well.

[Badger]

Sorry, if the month abbreviation is all upper case you will need a custom pattern

    grok {
        pattern_definitions => {
            "CUSTOMMONTH" => "(JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)"
            "CUSTOMTIMESTAMP" => "%{YEAR}-%{CUSTOMMONTH}-%{MONTHDAY} %{TIME}"
        }
        match => { "message" => "%{CUSTOMTIMESTAMP:timestamp}" }
    }